Propeller



Dec. 7, 1943. A P. F. HACKETHAL 2,336,012

5 Sheets-Sheet 1 Dec. 7, 1943.

P. F. HACKETHAL PROPELLER Filed Sept. lO, 1940 5 Sheets-Sheet 2 Dec. 7, 1943. P.' F. HACKETH'AL 2,336,012

PROPELLER- Filed sept. 1o, 1940 5 Sheets-sheet 45 pl v l l @il @in f 23 Syvum/vilo@ d -WO Patented Dec. 7, 1943 UNITED STATES PATEN? ostia PROPELLER Paul'F. Hackethal, Baltimore, Md., assigner to Everel Propeller Corporation,-Baltimore, Md., a corporation of Maryland Application September 10, 1940, Serial No. 356,226

6 Claims.

'This invention relates to propellers,A and more particularly has reference to a shank for an airplane propeller. The shank in question is for use especially with a` non-metallic propeller blade, such as for instance one composed of laminated wood or a plastic composition.

It will of course be appreciated that propeller blades are subjected to excessive strains during operation, and this is particularly true of blades (Cl. 1Y0-173) disclosed in the drawings which are appendedv hereto, and in which:

Figure-1 is a plan view of a wooden propeller blade and one specific form of shank.

that automatically adopt varying degrees of pitch Figure 2 is an end view oi the blade mounted during flight. Considerable dilculty has been upon the shankp experienced heretofore in securing a satisfactory Figure 3 iS an exploded View 0f the elements means for attaching a wood or plastic blade to of a wooden blade and the attaching shank.

the hub of an airplane drive shaft. such a- Figure 4 is e View of the blade end shank device of course must in the flrst place insure a mounted in a hub t0 Permit automatic adjustiirm attachment oi the blade to the hub, and mer-1110i the Pitch 0f the bladeat the same time must be of light weight .and Figure 5 is a view along the line 5-5 of Figmust' present a minimum air resistance. Obvlure 2 looking in the direction of the arrows.

ously it is desirable to provide a structure that Figure 6 lS a View along the line 6-5 0l Figure may be readily assembled, 5 looking in the direction of the arrows.

An object of this invention is to overcome the Figure 'I is a view along the line 'l-T of Figure disadvantages of the prior art and to provide a 5 looking inthe direction of the arrows. blade attachment or shank that will insure safety Figure 8 is a view of a modified form of shank y and optimum operating eiliclency. and pin. f

Another object of this invention is to provide Figure 9 is a sectional view of a blade mounted a shank member which may be securely inserted upon the shank of Figure 8. within a blade and which will afford an attach- Figure 10 is a sectional view along the line ment ior the blade that will withstand the various p lll-l0 of Figure 9 looking yin the direction of forces to which the blade is subjected. the arrows.

A still further object o! this invention is to Figure 11 is a sectional view along the line provide a shank that permits the blade to have an ll-ll of Figure 9 looking in the direction of airfoil shape in close proximity to the hub, therethe arrows. by insuring that the blade will serve to cool the Referring to the form of device disclosed in engine. Figures 1-7, and particularly to Figure 3, the

Yet another object of this invention is to proshank, designated generally A, consists of a. 'vide a metallic shank for a wooden propeller spindle l which is mounted within the hub. This blade that is particularly adaptable for use in a spindle is formed of metal and is preferably variable pitch propeller. cylindrical and provided with a recess 2 in order To accomplish the above and other important to decrease the weight. objects, my invention in general embraces the 40 While the invention may be employed tofatconcept of a shank mounted in a propeller hub tach a blade B to any type of hub, for purposes of and supporting the propeller blade, which inillustration I have shown in Figure 4 the shank `:lures a secureattachment of the blade to the mounted in a hub designated generally 3 which hub. More specifically, the shank is provided with Permits the blade to automatically vary its Ditch an extension which lies within the blade, and with changing conditions of flight. Briefly, the that portion oi the shank exterior or the blade hub is Provided with a recess 4 within which the is reduced, within sale aeronautical practice, to a drive shaft is keyed, and the shank is seated withminimum in order to afford as little air reslstin a block 5 that is rotatable within the casing. ance as possible. The extension itself insures a The longitudinal axis of the blade and shank is rigid attachment oi the blade to the shank, but disposed at an angle to the axis of rotation of added securement is afforded by certain pin memthe block 5, and consequently rotation oi the block bers extending through aportion oi the'blade and -will cause the blade to describe the arc of a the shank extension. Furthermore a clamp ex. cone duringwhich its pitch will vary. It is to be tending around the portion of the blade housing understood, however, that the shank may be the shank extension may be employed to give 66 used with any type of hub, regardless of whether the hub is for a xed o'r variable pitch propeller.

Inthe form of device shown in Figures 1-7, I preferably employ a flange 6 against which the end of the propeller abuts. It will be noted that this ange is of airfoil section and is set perpendicular to the shank axis. In order to decrease weight, recesses 1 may be cut in the flange, and apertures 9 may extend through the flange to permit the introduction of a liquid filler material into the propeller blade 'after assembly of the propeller upon the shank. Such apertures are especially desirable when a wooden blade is used and a sleeve is :dtted upon the exterior of the blade as will be referred to hereafter. In such case, the injection of the liquid serves to fill any pores in the wood or any crevices that may result during the assembly of the blade and shank.

Extending from the ange 6 is an extension or plate 9 which fits within the end of the blade. The plate 9 is of diminished thickness as compared to the diameter of the spindle I, and in top plan, as best shown in Figure 5, its sides incline away from the flange 6, thus presenting surfaces which resist any pull exerted onthe propeller by virtue of centrifugal force. It will be noted that the plate 9 is provided with a hole I9 therein which is adapted to receive a plug or `a pin Il as will be later described.

I have shown the shank as applied to wooden blades, and it will be appreciated that most wooden blades are made up of laminated strips, by reason of which a particularly ready assembly of my shank and blade is afforded. Referring particularly to Figure 6, I have shown a blade composed of ve strips designated generally I2, I3A, I3B, MA and IIB. The center strip, I2, is cut to form a recess corresponding to the perimeter of the plate 9, and this strip and plate are preferably of the same thickness.

As best shown in Figures 6 and '1, the pin II is of greater length than the thickness of the plate 9 and therefore extends beyond the plate surfaces. Strips ISA and I3B are drilled to provide recesses I5A and ISB which are adapted to receive those portions of the pin II extending beyond the face of plate 9. It will therefore be noted that the pin II affords a support for strips I3A and I3B which, in addition to the support of strip I2 afforded by the plate 9, serves to securely hold the complete bladeupon the shank A.

I have also shown a clamp or sleeve I6 which may be fitted around the iner end of the assembled blade B and secured to the ange 6 by spot welding or other suitable means. This band affords additional strength to the assembled blade and shank both insofar as insuring that the several laminations will remain assembled as a unit, and also compresses the wood fibers of strip I2 which lie between the inclined surfaces of the plate 9 and such sleeve. In this latter connection. it will be appreciated that, as a result of centrifugal force, the inclined surfaces will exert a force upon the corresponding surfaces of the recess in strip I2 which, if unresisted, will tend to work the blade free from the shank. The normal strength of the wood fibers in most cases will sulce to prevent any unseating of the plate within the recess of strip I2, but obviously the sleeve I6 will' compress the bers to entirely prevent anytendency ltoward loosening the ilt between the plate 9 and the propeller blade. .j

In assembling the blade upon the shank. rstrip I2 is rst cut out to provide the recess'for plate 9. and strips ISA and I3B are drilled to a depth to receive the pin II. The contacting surfaces of strips I2, I3A and I3B are painted with a suitable binder, such as glue, and these strips are assembled upon the plate 9 and pin I I. Like- Wise a suitable binder is applied to strips 14A, and IIB which in turn are assembled upon strips I3A and I3B, and the several strips subjected to suillcient pressure for a period of time to insure firm adhesion. The blade is then cut to the desired shape and the sleeve I6 assembled on the y blade and flange 6. -A ller'may be injected into the base of the blade through apertures 8 in the flange 6, and the assembled blade and shank then mounted in the hub which, as previously indicated, may be of any desired type.

While, in Figures 1-7, I have disclosed the use of a flange 6 upon the shank and alsothe use of a sleeve or clamp I6, I desire to point out that under some conditions one or the other of these two elements, or both, may be omitted.

It will be noted that the use of the shank described above, as well as the form of shank to be ext described, allows the blade to be shaped as an airfoil right down to its inner extremity which abuts 'against the flange 6. By thus providing an airfoil shape adjacent the hub, the blade impels a stream of air upon the engine which, particularly in the case of an air-cooled engine, con tributes to the cooling of the engine;

Referring now to the form of device shown in Figures 8-11, the shank designated generally C is made up of a spindle 2| which carries a plate 22. The plate 22 is joined to the spindle 2I by means of a sloping web 23. 'I'he plate 22 is, in general, triangular in shape, providing straight and angular shoulders 24 extending from the sides of the web 23. The plate 22 is drilled with a suitable number of holes 25 which, in the case of the device shown in Figures 8-11, are five in number.

I have disclosed a wooden propeller mounted upon the shank C, which, as heretofore described in connection with the first form of device, may be made up of laminated st rips 26, 21A, 21B, 28A and 28B. Strip 26 is of the same thickness as plate 22, and a recess is cut therein corresponding to the shape of plate 22. It will be noted that the several strips extend back to abut against the base of spindle 2l, and shoulders 24 on the plate, together with the pins which extend through the plate 22, later to be described, serve to maintain the blade securely, in place against such base. Pins 29 in the form of tubes fit within the holes 25, and as best shown in Figures 10 and 11, are of a length to extend through the strips 21A and 21B. These strips therefore are drilled to receive such pins prior to the assembly of -the several strips to form the complete blade. It might be pointed out that I contemplate an assemblyof the. several laminated strips in the same way as described above in connection with Figures 1-7.

I have shown a sleeve or clamp 3l surrounding the butt of the blade which serves to aiord additional strength to the assembled blade and shank. However, I wish it to be understood that this sleeve may be omitted under certain conditions, particularly where the liber of the' wood and the type of binder is of suiiicient strength to withstand all conditions which may be encountered in operation.

It will be noted .that in Figures 8-11 no ange is disclosed corresponding to the flange 6 of the ilrst described device, but itshould be pointed out that such a ange may be employed if desired.

While I have described my invention with reference to a wooden blade, and while it ilnds especial application in such a blade, it will be appreciated that either form of shank may be used with other types of blades. and, in this connection, I would mention particularly blades made up fr'om plastic compositions or metals which could not be readily attached directly to the hub.

While I have shown and described the preferred embodiment of my invention, I wish it to be understood that I do not confine myself to the prehaving an airfoil shape 'and size identical with the root face of the blade, and an anchor extend-A ing from the flange as an-extension of the shank and having a. substantially trapezoidal configuration with its shorter parallel side immediately adjacent the flange, said blade having a socket of a configuration identical to that of the anchor, said blade being of laminated construction and assembled about the extension.

2. In a propeller assembly, a hub, a blade, and a shank member serving to mount the blade upon the hub, a transverse flange on the shank member for engaging the root end face of theblade,l

an anchor extending from the flange as an extension of the shank and having a portion remote from the flange of greater transverse dimension that the portion immediately adjacent the flange,

vsaid blade having a socket of a. configuration identical to that of the anchor, said blade being the hub. a transverse'ange on the shank member for engaging the root end face of the blade. and

. an anchor extending `from the flange as an extension of the shank and having a portion remote from the flange of greater transverse dimension than the portion immediately adjacent the flange, said blade having a socket of a configuration identical to that of the anchor, said blade being of laminated construction and assembled about the extension, said nange having an aperture therein for the injection of a iller ui'd into the I root end of the blade.

- 4. In a propeller assembly, a hub, a blade, and l a shank member serving to mount the blade upon the hub, a flange on the shank member, and a member extending from said ange, said extension member being securely seated entirely wthin a recess in the blade and serving vto maintain the blade in abutting position against the vilange, said flange having an opening therein forinjection of a filler fluid into the adjacent end of the blade.

5. In a propeller assembly, a hub, a blade, 'and a shank member serving to mount the blade upon the hub, a flange on the shank member, an anchor of trapezoidal configuration forming an axial extension of the shank with the shorter of the parallel sides of said trapezoidal anchor adjoining said flange, said blades having a recess in the root of laminated construction and assembled about the extension, and a ferrule surrounding the root of the blade and secured to said flange to prevent lateral expansion of the root of the blade and thereby retain the blade assembled on the anchor.

3. In a propeller assembly, a hub, a blade, and a shank member serving to mount the blade upon thereof of a configuration identical to the anchor for receiving the anchor and maintaining the root of the blade vin abuttingengagement with the flange.

6. In a propeller assembly, a hub, a. blade, and a shank member for mounting the blade upon the hub, an anchor member formed on the shank and constituting an axial continuation thereof, said anchor member having a trapezoidal configuration with its shorter parallel side adjoining the shank, the root of said blade having a socket therein of a configuration identical to that of the anchor for the receptionof said anchor, and a l ferrule surrounding the root of the blade to prevent lateral expansion of the blade and thereby .v

maintain the blade in intimate engagement with the anchor.

.. PAUL F. HACKEIHAL. 

